Making a Compass - More Fun With Magnets

I was regaling my oldest, this morning, with a list of scientific, and sociological errors from Columbia Picture's 2012, which my husband and I watched last night, after the kids were in bed. The movie really is so bad, it's almost good. (I grabbed the movie poster, at the right, from Wikipedia)

Besides the worst ever Schwarzenegger impersonation, there was also CNN calmly reporting on a South American earthquake, when California had just fallen into the Pacific, and Yellowstone had erupted, killing the vice president in an ash cloud. And, then there was the fact, that even after the magnetic poles of the earth had shifted, without the knowledge of the main characters, they were still able to fly by instrumentation to their selected destination.

The children wanted to know why the earth's magnetic poles would have mattered. I explained to them that while the compass rose printed on a map would stay the same, if the poles shifted, the direction of north and south, would change on all the compasses. So, if the characters in the movie, followed the plane's compass directions, they would no longer end up, where they thought they were heading.

Imagine silent, blank stares from the children...clearly, we needed to make a compass.

As, I gathered a bowl of water, a cork, a needle, and a magnet from the fridge, I reminded them, that the earth is a large magnet - with a north pole at the top, and a south pole at the bottom.

After I pre-poked a hole through the cork, the children magnetized the needle, by rubbing it 20 times, in the same direction across the magnet.

Then, they stuck the needle through the cork...

...and dropped it into the water.

No matter which way they dropped it in, it always turned, and stopped, pointing north. North, is easy in our valley, because we have mountain ranges running to our east, and west, since our needle pointed between the mountain ranges, we knew it was, indeed, pointing north.

We made a second compass, just to double check, and although I forgot to snap a picture, I'm sure you know, it pointed in the same direction.

I showed the children that if they rubbed the needle in the opposite direction on the magnet, the needle would seem to point south.

Then, I lost them, to the fun of playing with floating corks in a bowl of water, but I think they got the idea.

It's great to be a homeschooler.